Fox worked hard to conceal his symptoms from the outside world, and he expressed relief at making his condition known to the public. It was difficult to hide his symptoms as they got worse: tremors would shake his whole arm, or he'd have trouble walking because of muscle stiffness or severe shaking in his legs. About Parkinson's Disease Parkinson's disease afflicts approximately 1 million to 1.5 million people in the U.S., most of who are 60 yrs-old or older. The disorder is seen in people of all ethnic groups and among men and women in equal numbers. There is no known cause and no cure, just treatments to help control the symptoms of trembling arms and legs, trouble speaking, and difficulty coordinating movement. The disease can affect younger people such as Michael J. Fox. In fact, about 5-10% of cases are diagnosed in people younger than 40 years of age. The National Parkinson's Foundation reports that the average age of onset is 55.

Parkinson's disease occurs when neurons degenerate (lose the ability to function normally) in a part of the brain called the substantia nigra. Many of these neurons that degenerate contain the neurotransmitter called dopamine. As these neurons degenerate, dopamine levels fall, and the balance between dopamine and other neurotransmitters, such as acetylcholine, is thrown off. This leads to muscles that do not work normally. Muscles may contract and relax, causing shaking called tremors. Sometimes if muscles contract but do not relax a part of the body can become rigid. Injections of dopamine do not fix this deficiency because dopamine cannot cross the blood-brain barrier to reach the brain. Drugs Can Control Some Synptoms Medication helps reduce the shaking in many patients. Doctors have told Fox that he probably has about 10 more years of relatively normal life before the symptoms will start interfering with his day-to-day activities. A drug developed in the 1960s called levodopa (L-dopa) was the first drug used to reduce the symptoms of Parkinson's disease. It helps boost dopamine levels in the brain because it can cross the blood-brain barrier. Other drugs block acetylcholine and aim to restore the dopamine-acetylcholine balance. Now there are numerous drugs available, many of which are used in combination for a better effect. Unfortunately, many of the drugs become less effective over time. Therefore, as the disease progresses, there are fewer treatment options.

Brain Surgery Research has shown that a surgery called thalamotomy can often help people with Parkinson's disease regain control over their limbs. The thalamus is an oval shaped structure in the forebrain; it is about 3 cm (1 inch) in length. The thalamus acts as a relay station for sensory information, such as input for touch, hearing, vision, and taste. It also functions in part to interpret this information--is something hot or painful, for example. It also plays a role in voluntary motor actions, such as when a person wants to move a certain muscle (such as lifting an arm). Fox elected to have this surgery in 1998, and had part of his thalamus removed. The surgery took four hours, during which time Fox was awake to help the surgeons. As they located and cauterized (using heat to destroy cells that were misfiring) the necessary part of the thalamus, Fox gave important feedback as to what area of his body was being affected by the work they were doing on his brain. At one point, his speech began to slur, and the surgeons stopped working on that area. The surgery was a success, freeing Fox of his most serious tremors. The surgery has a 90% success rate, although there are risks: paralysis, coma, or death.

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